Simulating northern bobwhite population responses to nest predation,nesting habitat,and weather in south Texas

Nest predation is thought to be one of the major factors limiting northern bobwhite (Colinus virginianus) populations. We examined the relative impact of altering nest-predation rate, nesting habitat, and weather (i.e., temp and precipitation) on northern bobwhite population dynamics in a hypothetical 15,000-ha subtropical-rangeland ecosystem in south Texas using a simulation model. The systems model consisted of a 3-stage (i.e., eggs, juv, and ad) bobwhite population with dynamics influenced by variables affecting production, recruitment, nest predation, and mortality. We based model parameters on data collected from a 3-yr nest-predator study employing infrared-camera technology, from ongoing field research using a radio-marked population of wild bobwhites, and from the literature. The baseline simulated bobwhite population dynamics corresponded closely to empirical data, with no difference between medians of simulated (n = 30 yr) and observed bobwhite age ratios over a 28-yr period. Similarly, a time-series comparison of simulated and observed age ratios showed most (89%) observed values fell within the 5th and 95th percentiles of the simulated data over the 28-yr period. We created simulated population scenarios representing 1) baseline historical conditions, 2) predator control, 3) low precipitation, 4) low precipitation with predator control, 5) high temperature, 6) high temperature with predator control, 7) reduced nest-clump availability, and 8) reduced nest-clump availability with predator control that resulted in considerably different median bobwhite densities over 10 yr. For example, under simulated predator control, populations increased by about 55% from the baseline scenario, whereas under simulated reduced nest-clump availability, populations decreased by about 75% from the baseline scenario. Comparisons of time-series for each scenario showed that reduced nest-clump availability, low precipitation, and high temperature reduced bobwhite densities to a larger degree compared to a natural nest predation rate. Reduced nest-clump availability resulted in the most substantial decline of simulated bobwhite densities. Simulations suggested that management efforts should focus on maintaining adequate nest-clump availability and then possibly consider nest predator control as a secondary priority. © 2010 The Wildlife Society     

Life beneath the surface of the central Texan Balcones Escarpment: genus Anillinus Casey, 1918 (Coleoptera,Carabidae, Bembidiini): new species,a key to the Texas species,and notes about their way of life and evolution

The Texas fauna of the genus Anillinus Casey, 1918 includes three previously described species (A. affabilis (Brues), 1902, A. depressus (Jeannel), 1963 and A. sinuatus (Jeannel), 1963) and four new species here described: A. acutipennis Sokolov & Reddell, sp. n. (type locality: Fort Hood area, Bell County, Texas); A. comalensis Sokolov & Kavanaugh, sp. n. (type locality: 7 miles W of New Braunfels, Comal County, Texas); A. forthoodensis Sokolov & Reddell, sp. n. (type locality: Fort Hood area, Bell County, Texas); A. wisemanensis Sokolov & Kavanaugh, sp. n. (type locality: Wiseman Sink, Hays County, Texas). A key for identification of adults of these species is provided. The fauna includes both soil- and cave-inhabiting species restricted to the Balcones Fault Zone and Lampasas Cut Plain and adjacent areas underlain by the Edwards-Trinity Aquifer. Based on morphological and distributional data, we hypothesize that four lineages of endogean Anillinus species extended their geographical ranges from a source area in the Ouachita-Ozark Mountains to the Balconian region in central Texas. There the cavernous Edwards-Trinity aquifer system provided an excellent refugium as the regional climate in the late Tertiary and early Quaternary became increasingly drier, rendering life at the surface nearly impossible for small, litter-inhabiting arthropods. Isolated within the Edwards-Trinity aquifer system, these anilline lineages subsequently differentiated, accounting for the currently known diversity. The paucity of specimens and difficulty in collecting them suggest that additional undiscovered species remain to be found in the region.     

Biomass: Is it a useful tool in paleocommunity reconstruction?

In general, more of the biomass of the community is preserved than is its numerical abundance. Thus, the paleontologist, on the average, works with more of the community when biomass is used. Community characteristics such as taxon dominance and habitat proportions are at least as accurately derived from biomass as numerical abundance. The use of biomass is clearly more appropriate in describing energy flow and trophic proportions. Whenever possible, biomass should be used as a complement to numerical abundance in future paleoecologic reconstructions.     

Development of Cuscuta species on a partially incompatible host: induction of xylem transfer cells

Summary.  The growth of dodders, Cuscuta reflexa and Cuscuta japonica, on the partially incompatible host poinsettia (Euphorbia pulcherrima) is studied. Poinsettia responds by bark growths to the formation of the dodder haustoria and prevents dodder from obtaining normal growth. The growth instead becomes extremely branched, coral-like, and dodder lacks the ability to form haustoria. After a period of coral-like growth, long shoots sprout, resembling the normal growth. These long shoots mark an ending phase for dodder, which dies shortly after without having flowered. During the coral-like growth phase, dodder develops transfer cells in the parenchyma cells bordering the vessels of the xylem in the shoot. The transfer cells have not been observed when dodder is grown on the compatible host Pelargonium zonale. A coral-like growth phase has also been observed at the establishing phase when dodder is grown in vitro on agar; later a more normal growth form takes over. In this coral phase, xylem transfer cells are also developed. The fluorochromes carboxyfluorescein and Texas Red were loaded into the host in the phloem and xylem, respectively, and detection of these fluorochromes in the dodder stem indicated that a functional haustorial contact developed for both vascular systems. The results show that Cuscuta spp. have the genetic ability to develop xylem transfer cells and use this in response to developmental stress. Received June 12, 2002; accepted August 26, 2002; published online March 11, 2003     

Detecting Karenia brevis blooms and algal resuspension in the western Gulf of Mexico with satellite ocean color imagery

Blooms of the toxic dinoflagellate, Karenia brevis, have had detrimental impacts on the coastal Gulf of Mexico for decades. Detection of Karenia brevis blooms uses an ecological approach based on anomalies derived from ocean color imagery. The same anomaly product used in Florida produces frequent false positives on the Texas coast. These failures occurred during wind-driven resuspension events. During these events resuspension of benthic algae significantly increases chlorophyll concentrations in the water, resulting in confusion with normal water column phytoplankton, such as Karenia. A method was developed to separate the resuspended chlorophyll from the water column chlorophyll, decreasing the false positives used with the detection method.     

Studies on methemoglobin reductase. Immunochemical similarity of soluble methemoglobin reductase and cytochrome b5 of human erythrocytes with NADH-cytochrome b5 reductase and cytochrome b5 of rat liver microsomes.

An antibody preparation elicited against purified, lysosomal-solubilized NADH-cytochrome b₅ reductase from rat liver microsomes was shown to interact with methemoglobin reductase of human erythrocytes by inhibiting the rate of erythrocyte cytochrome b₅ reduction by NADH. The ferricyanide reductase activity of the enzyme was not inhibited by the antibody, suggesting that the inhibition of methemoglobin reductase activity may be due to interference with the binding of cytochrorme b₅ to the flavoprotein. Under conditions of limiting concentrations of flavoprotein, the antibody inhibited the rate of methemoglobin reduction in a reconstituted system consisting of homogeneous methemoglobin reductase and cytochrome b₅ from human erythrocytes. This inhibition was due to the decreased level of reduced cytochrome b₅ during the steady state of methemoglobin reduction while the rate of methemoglobin reduction per reduced cytochrome b₅ stayed constant, suggesting that the enzyme was not concerned with an electron transport between the reduced cytochrome b₅ and methemoglobin.An antibody to purified, trypsin-solubilized cytochrome b₅ from rat liver microsomes was shown to inhibit erythrocyte cytochrome b₅ reduction by methemoglobin reductase and NADH to a lesser extent than microsomal cytochrome b₅ preparations from rat liver (trypsin solubilized or detergent solubilized) and pig liver (trypsin solubilized). The results presented establish that soluble methemoglobin reductase and cytochrome b₅ of human erythrocytes are immunochemically similar to NADH-cytochrome b₅ reductase and cytochrome b₅ of liver microsomes, respectively.     

Borate buffer inhibition of peroxidatic intermediate formation in the deutero-ferriheme-hydrogen peroxide system

The rate of formation of peroxidatically active reaction intermediate(s) via oxidation of the iron(III)-porphyrin complex, deuteroferriheme, with hydrogen peroxide decreases with increasing borate content of mixed borate-carbonate buffer solutions. Studies at pH = 9.25 in 0.035 M borate buffer and 0.035 M carbonate buffer suggest borate to function as an uncompetitive inhibitor. A comparison of slopes and intercepts of double reciprocal plots for inhibited and uninhbited reactions allows calculation of selected parameters for the deuteroferriheme-H₂O₂ reaction at pH = 9.25 in terms of a typical enzymatic stoichiometric mechanism for heme activity. This includes the Michaelis constant (K_m = 8.1 × 10^?5 M) and the first-order rate constant for conversion of heme-substrate complex to intermediate(s) (k₃ = 7.4 sec^?1). A tentative mechanistic model involving reversible interaction of borate inhibitor with heme-substrate complex is considered, and pseudo-first-order rate constants calculated on the basis of this scheme are in reasonable agreement with those obtained experimentally. It is suggested that comparable inhibitory action may be responsible for some previously reported cases of decreased catalase enzyme activity in borate buffer solutions     

Cosmetophilus vonones, N. G., N. Sp., (Apicomplexa: Actinocephalidae) in the Harvestman Vonones sayi (Arachnida: Cosmetidae)

The gregarine Cosmetophilus vonones , n. g., n. sp. (Sporozoasida: Actinocephalidae: Acanthosporinae) from the intestine and intestinal caeca of the harvestman Vonones sayi (Simon) (Opiliones: Cosmetidae) is described. The new internal parasite is the first recorded from a harvestman in the New World and the second from the opilion suborder Laniatores. In addition to the records from the type locality in western Texas, additional collections are reported from the same host in central and eastern Texas and Tennessee.     

Effects of Radiotransmitter Necklaces on Behaviors of Adult Male Western Burrowing Owls

Abstract: We studied the behavioral effects of necklace-style radiotransmitters on breeding male western burrowing owls (Athene cunicularia hypugaea) in 2 areas of northwestern Texas, USA, in 2004 and 2005. We tested the hypothesis that transmittered owls would spend time interacting with their necklaces and as a result spend less time in vigilance and resting activities than would nontransmittered owls. Nontransmittered owls (n = 6) spent significantly more time being vigilant (P = 0.007) than did transmittered owls (n = 3) in 2004, who spent significant amounts of time interacting with their necklaces. In 2005, behaviors of transmittered owls (n = 8) were significantly different (P < 0.001) from control individuals (n = 4), but behaviors did not vary consistently by treatment period (prenecklace vs. necklace vs. postnecklace periods). Behavioral activity budgets varied considerably among individuals. Although the owls spent a significant amount of time interacting with their necklaces, they appeared to habituate to the presence of the transmitters within a relatively short period (<1week), and necklaces did not affect survivorship or fitness in the short-term.